It's a side effect of a fix we added that affected users with uncalibrated joysticks, that had the airplane slewing away when they entered the editor, so we automatically disabled the joystick on activating the editor and re-enabled it when exiting.
Unfortunately, it seems that FSX also disables the pan with spacebar+mouse when disabling the joystick, which doesn't seem to be very consistent ( the official name for that event is "JOYSTICK CALIBRATE", but it doesn't really calibrate, it disables it...).
You can fix the problem momentarily by pressing CTRL+K as soon as you enter the editor.
In any case, we made that setting optional with a parameter in the [GSX] section of the Couatladdons.ini file
editor_joystick_disabled = 0 (0 it's the default)
In the current version, which can get by reinstalling GSX (Beta) or the Couatl 3 Public Beta. So, we'll just have to tell users that are affected by the joystick calibration problem to set it to 1, and have the editor automatically disable it when entering (they will have to zoom/pan with the keyboard).
